The surface chemistry of nanoparticles and their interactions with the base material are very important factors, among lots of others like moisture adsorption and nanocomposite processing method, which affect the electrical performance of nanodielectrics. This study tries to reveal the main factors that affect the electrical behavior of silicon nitride/epoxy nanocomposites. Firstly, the concentration was on the processing method in order to determine the best way of dispersing the particles and preparing the nanocomposite samples. However silicon nitride/epoxy nanocomposites show insignificant sensitivity to the processing methods employed in this study. Further experiments indicate that the main factor controlling the electrical behavior of such composites might be the presence of the amine groups on the surface of the silicon nitride particles. This affects the resin/hardener stoichiometric ratio which is thought to facilitate charge mobility through the polymeric matrix, eventually leading to a lower breakdown strength.